Functional Residual Capacity Under Apnoeic Oxygenation with Different Flow Rates in Children

NCT ID: NCT05672329

Last Updated: 2024-09-19

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 108 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2023-01-09
• Study Completion Date: 2024-05-02

Brief Summary

During induction of general anaesthesia physiological breathing stops and needs to be artificially established with facemask ventilation, and finally tracheal intubation or placement of a supraglottic airway. During the airway management, when lungs are not or only poorly ventilated, there is a risk for atelectasis. These atelectasis can contribute to respiratory adverse events (e.g. pulmonary infection or respiratory insufficiency) during or after general anaesthesia. High-flow nasal oxygen (HFNO) is the administration of heated, humidified and blended air/oxygen mixture via a nasal cannula at rates ≥ 2 L/kg/min. HFNO used during airway management (i.e. intubation) can extend the tolerance for apnea, the time from end of physiological breathing until artificial ventilation is established. The main objective of this study is thus to investigate the variations of poorly ventilated lung units (i.e., silent spaces) as a surrogate for functional residual capacity measured by electrical impedance tomography to dynamically assess atelectasis formation and regression under apnoeic oxygenation with different flow rates.

Detailed Description

High-flow nasal oxygen (HFNO) is the administration of heated, humidified and blended air/oxygen via nasal cannula at rates ≥ 2 L/kg/min. HFNO is an open system that can be used with nasal prongs of different sizes and was developed in neonatal intensive care unit for preterm babies with apnoea as alternative to continuous positive airway pressure (CPAP). Due to its ease of use and safety to apply to a wide range of indication HFNO is increasingly gaining interest for providing respiratory support in paediatric patients and in adults in ICU with respiratory failure. In adult populations, the use of HFNO permits to prevent desaturation during tracheal intubation of intensive care patients with mild-to-moderate hypoxemia. An application for HFNO in adults and children, is the extension of safe apnoea in patients who were undergoing general anaesthesia for hypopharyngeal or laryngo-tracheal surgery. This method, the so-called safe apnoeic oxygenation, also prevents hypoxemia in children during intubation. By using this technique, Patel et al. demonstrated a significate prolongation of apnoea time and proposed a ventilatory effect, as these studies revealed a slower increase in pCO2 than physiologically was expected. In these studies, researchers compared their data to studies from the 1950-ies, where CO2 increase during apnoea was investigated. In contrast, the investigators' previous research projects with HFNO did not confirm the claimed ventilatory effect in children and adults.

Furthermore studies performed in spontaneously breathing neonates and adults have shown the ability of HFNO to generate some increase in pharyngeal pressure, which could explain the improvement of oxygenation despite prolongation of apnea time. The investigators' previous study on adult patients showed that a relevant increase of pressure was nearly absent while patient's mouth was open. Currently, there is no data on the physiological pressure that is generated in the subglottic airway in apneic children treated with HFNO. The traditional measurement of intratracheal pressure with a catheter in the trachea is considered to pose a risk in small children.

The main objective of this study is thus to investigate the variations of poorly ventilated lung units (i.e., silent spaces) as a surrogate for functional residual capacity measured by electrical impedance tomography to dynamically assess atelectasis formation and regression under apnoeic oxygenation with different flow rates.

Eligible children will receive premedication with Midazolam rectal/oral 0.5 mg/kg or Dexmedetomidine nasal 2 mcg/kg 30 minutes before the beginning of the procedure (local SOPs of the paediatric anaesthesia departments). Mandatory monitoring will consist of non-invasive peripheral oxygen saturation (SpO2), heartrate (HR), and non-invasive blood pressure (NIBP). An intravenous line for drugs injection will be placed.

After start of anaesthesia (="induction"), adequate face-mask ventilation will be established. The sealed envelope for randomisation will then be opened. Standard anaesthesia will be continued using of intravenous propofol. Anaesthetic depth will be assessed using NarcotrendTM (NarcotrendTM, Hannover, Germany), maintaining values between 40 and 60. Additional study related non-invasive monitoring: transcutaneous tcCO2 and O2 (ToscaTM, Radiometer, Neuilly-Plaisance, France) measurement, thoracic electrical impedance tomography (EIT, PulmoVista 500, Draeger, Luebeck, Germany) and NIRS (Niro-200NX (Hamamatsu, Tokyo, Japan). ECG, pulse-oximetry, blood pressure, Narcotrend (NarcotrendTM, Hannover, Germany), thoracic EIT will be measured continuously, starting before induction while spontaneous breathing and ending 1 minute after the recruitment-manoeuvre. All patients will receive neuromuscular blockade medication of 2 x ED95 (standard intubation dose) to facilitate airway management. Neuromuscular block will be assessed using train-of-four (TOF) monitoring (TOF-Watch, Organon Ltd, Dublin, Ireland). A TOF value of zero before apnoea start and throughout the whole procedure will be deemed essential.

After that one minute of pressure support mask ventilation (Pmax 20 cm H20) with a backup respiratory rate of 20/min, normalized at a volume of 6-8 ml.kg-1 with 100% oxygen and will be applied. The ventilation will be discontinued, and the child will be left apnoeic for 5 minutes receiving oxygen according to the randomisation.

Children will be randomized to receive three different flow rates of 100% oxygen, warmed and humidified with the OptiFlow device (Fisher&PaykelTM, Auckland, New Zealand):

• group 1): 0.2 l/kg/min + continuous jaw thrust
• group 2): 2 l/kg/min + continuous jaw thrust
• group 3): 4 l/kg/min + continuous jaw thrust (control group)
• Group 4): 2 l/kg/min with OptiFlow FiO2 1.0 using OptiFlow-Switch system by Fisher&Paykel.

The nostrils must not be occluded by the nasal cannula by more than 50%. The time until desaturation from SpO2 100% to SpO2 95% will be measured. A chest ultrasound at end of intervention after definitive airway management will prove that no pneumothorax developed during the procedure.

Break-up criteria during apnoea are: SpO2 below 95%, transcutaneous CO2 above 70 mmHg, or time of apnoea >5 minutes, a decrease of NIRS >30% from baseline.

Conditions

Apnea; Anesthesia; Intubation Complication; Children, Only; Apnea Infant; Atelectasis; Ventilation Therapy; Complications

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: PREVENTION
• Blinding Strategy: SINGLE

Study Groups

Group 1: Low-flow apnoeic oxygenation

Group 1) 0.2 L/kg/min using OptiFlow system by Fisher\&Paykel and an oxygen inspiration concentration FiO2 of 1.0;

Group Type: EXPERIMENTAL

0.2 L/kg/min, FiO2 1.0 + continuous jaw thrust

Intervention Type: OTHER

Apnoeic Oxygenation with flow rate 0.2 L/kg/min using OptiFlow system by Fisher\&Paykel and an oxygen inspiration concentration FiO2 of 1.0

Group 2: High-flow apnoeic oxygenation

Group 2) 2 L/kg/min using OptiFlow system by Fisher\&Paykel and an oxygen inspiration concentration FiO2 of 1.0;

Group Type: EXPERIMENTAL

2 L/kg/min, FiO2 1.0 + continuous jaw thrust

Intervention Type: OTHER

Apnoeic Oxygenation with flow rate 2 L/kg/min using OptiFlow system by Fisher\&Paykel and an oxygen inspiration concentration FiO2 of 1.0

Group 3: Control group apnoeic oxygenation

Group 3) 4 L/kg/min using OptiFlow system by Fisher\&Paykel and an oxygen inspiration concentration FiO2 of 1.0;

Group Type: ACTIVE_COMPARATOR

4 L/kg/min, FiO2 1.0 + continuous jaw thrust

Intervention Type: OTHER

Apnoeic Oxygenation with flow rate 4 L/kg/min using OptiFlow system by Fisher\&Paykel and an oxygen inspiration concentration FiO2 of 1.0

Group 4: High-flow apnoeic oxygenation

Group 4): 2 l/kg/min with OptiFlow FiO2 1.0 using OptiFlow-Switch system by Fisher\&Paykel

Group Type: EXPERIMENTAL

2 L/kg/min using OptiFlow-Switch system, FiO2 1.0 + continuous jaw thrust

Intervention Type: OTHER

Apnoeic Oxygenation with flow rate 2 L/kg/min using OptiFlow-Switch system by Fisher\&Paykel and an oxygen inspiration concentration FiO2 of 1.0

Interventions

0.2 L/kg/min, FiO2 1.0 + continuous jaw thrust

Apnoeic Oxygenation with flow rate 0.2 L/kg/min using OptiFlow system by Fisher\&Paykel and an oxygen inspiration concentration FiO2 of 1.0

Intervention Type: OTHER

2 L/kg/min, FiO2 1.0 + continuous jaw thrust

Apnoeic Oxygenation with flow rate 2 L/kg/min using OptiFlow system by Fisher\&Paykel and an oxygen inspiration concentration FiO2 of 1.0

Intervention Type: OTHER

4 L/kg/min, FiO2 1.0 + continuous jaw thrust

Apnoeic Oxygenation with flow rate 4 L/kg/min using OptiFlow system by Fisher\&Paykel and an oxygen inspiration concentration FiO2 of 1.0

Intervention Type: OTHER

2 L/kg/min using OptiFlow-Switch system, FiO2 1.0 + continuous jaw thrust

Apnoeic Oxygenation with flow rate 2 L/kg/min using OptiFlow-Switch system by Fisher\&Paykel and an oxygen inspiration concentration FiO2 of 1.0

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• Written informed consent by legal guardian
• Paediatric patients undergoing elective surgery requiring general anaesthesia at the Bern University Hospital - Inselspital in Bern
• Child weight between 10-20kg
• American Society of Anesthesiology (ASA) physical status 1 & 2 (healthy child, no severe co-morbidities)

Exclusion Criteria

• Known or suspected difficult intubation
• Oxygen dependency
• Congenital heart or lung disease
• Obesity BMI (kg/m2) >30
• High aspiration risk (requiring rapid sequence intubation).

• Maximum Eligible Age: 16 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Thomas Riva

OTHER

Sponsor Role: lead

Responsible Party

Thomas Riva

Prof. Dr. med.

Responsibility Role: SPONSOR_INVESTIGATOR

Principal Investigators

Alexander Fuchs, M.D.

Role: PRINCIPAL_INVESTIGATOR

Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital,

Thomas Riva, M.D.

Role: STUDY_DIRECTOR

Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital,

Locations

Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern

Bern, Canton of Bern, Switzerland

Countries

Switzerland

References

Lippuner R, Pellaud C, Huber M, Greif R, Disma N, Riva T, Fuchs A, Riedel T. Efficacy of a lung recruitment manoeuvre in children undergoing general anaesthesia with a supraglottic airway. Br J Anaesth. 2025 Nov;135(5):1537-1542. doi: 10.1016/j.bja.2025.08.016. Epub 2025 Sep 23.

Reference Type: DERIVED

PMID: 40993003 (View on PubMed)

Other Identifiers

Fuchs-Riva2022

Identifier Type: -

Identifier Source: org_study_id